In the pulp and paper industry, the chipping of wood is often performed by means of disk chippers. In a chute-fed disk chipper, such as is seen in FIGS. 1 and 2, the logs (not shown) are fed against a knife disk 13 of the chipper along an inclined feed spout or chute 47 with the aid of gravity. The knife disk 13 rotates around a horizontal axis or around an axis that is inclined, usually at a maximum angle of 20.degree.. To the disk knife 13 are attached, essentially radially, knives 14 that chip the logs against a fixed bedknife 4 located in the lower part of the feed spout. The bedknife is occasionally also referred to as an anvil or a counterblade. The bedknife 4 is subjected to considerable shock forces and must therefore be firmly secured to the chipper frame 29.
During chipping, the logs slide against the bedknife 4 toward the knife disk 13 and wear the bedknife heavily. The wear depends on the number of runs, on the quality of the wood and on the quality and amount of inorganic matter that may occur on the surface of the logs. Because of said wear, the bedknife 4 typically has to be replaced at intervals of 1 to 12 weeks, depending on the circumstances.
A common way of fastening a bedknife 4 to the frame 29 is to use a number of screws 5, 6, 7, and 8 parallel to the axis of the knife disk 13, in a manner similar to the manner shown in FIGS. 1 and 2. In addition, the bedknife 4 is pushed against the framework 29 of the disk chipper from above by means of a screw-on feed spout 47 so that the bedknife is essentially pinched between the feed spout and some other portion of the chipper frame. When the bedknife 4 is to be replaced, it is also necessary to unscrew some (or all) of the fastening screws 12 (FIG. 1) of the feed spout 47 and to raise the feed spout. Before the feed spout 47 can be lowered and fixed into position, the new bedknife 4 has to be set and fixed in place by means of the screws 5-8. Furthermore, the space between the feed spout 47 and the frame 29 must be cleaned carefully. The replacement of a bedknife 4 is hence a relatively laborious and time-consuming operation.
It is desirable to provide a less laborious and time-consuming method for fastening a bedknife in a disk chipper. It is further desirable to provide a disk chipper on which a bedknife is fastenable in a less laborious and time-consuming manner.
In accordance with one aspect of the present invention, a method for fastening a stationary bedknife for a disk chipper to a chipper frame is provided. According to the method, a first surface of a bedknife is positioned relative to a first surface of a chipper frame. A wedge is moved between a second surface of the bedknife opposite the first surface of the bedknife and a second surface of the chipper frame opposite the first surface of the chipper frame so that the bedknife is held in place between the wedge and the first surface of the chipper frame.
In accordance with another aspect of the present invention, a disk chipper includes a bedknife, the bedknife having opposing first and second surfaces, and a chipper frame, the chipper frame having an opening for receiving the bedknife, the opening being defined by opposing first and second surfaces for facing the first and second surfaces of the bedknife, respectively. The disk chipper further includes a wedge, the wedge being movable in a first direction between the second surface of the bedknife and the second surface of the chipper frame to move the first surface of the bedknife in a second direction substantially perpendicular to the first direction toward the first surface of the chipper frame.